Hybrid CPU Scheduling algorithm SJF-RR In Static Set of Processes

Abstract

Round Robin (RR) algorithm is widely used in modern operating systems (OS) as it has a better responsiveness as periodic quantum (occurring at regular intervals) in addition to have a good feature such as low scheduling overhead of n processes in a ready queue which takes a constant time O(1). But, RR algorithms have the worse features such as having low throughput, long average turnaround and waiting time, in addition to the number of context switches for (n) processes is (n) switches. Shortest Job First (SJF) however, itself is not practical in time sharing Oss due to its low response. More over the scheduling overhead of n processes in a ready queue is O(n), But the good features of SJF algorithm are the best average turnaround time and waiting time.By considering a static set of n processes, desirable features of CPU scheduler to maximize CPU utilization, response time and minimize waiting time and turnaround time are obtained by combining the kernel properties of SJF algorithm with the best features of RR algorithm to produce a new algorithm as an original and novel algorithm called; " Hybrid CPU Scheduling algorithm SJF-RR in Static Set of Processes " which, proposed in this research.The proposed algorithm is implemented through an innovative optimal equation to adapt time quantum factor for each process in each round as a periodic quantum (occurred at irregular intervals). That is while applying proposed algorithm, mathematical calculations take place to have particular time quantum for each process. Once, a criterion has been selected for comparison, deterministic modeling with the same numbers for input is proven that proposed algorithm is the best.